Neuropathic form of arthrogryposis multiplex congenita: Report of 3 cases with complete necropsy, including the first reported case of agenesis of muscle spindles

In 3 infants with arthrogryposis multiplex congenita (AMC) complete necropsy, including removal of the entire spinal cord, was performed. Histologically, spinal type (neurogenic) atrophy of skeletal muscles in conjunction with spinal motor neurone depletion, unaccompanied by noticeable gliosis, were the most prominent features common to all cases. In addition to these, one infant (Case 1) showed total absence of muscle spindles as evident from the examination of several hundred step-serial paraffin sections covering 11 different levels in 36 samples taken from a wide range of skeletal muscles of both upper and lower extremities. This is believed to be the first published case of agenesis of muscle spindles.